This application claims the benefit of the filing date under 35 U.S.C. 119(a) of Italian Patent Application No. IT PI99A000033 filed on Jun. 15, 1999.
The present invention relates to a machine for inserting insulating paper in the slots of armatures of electric motors.
Furthermore the invention relates to a method for operating the cutting and inserting devices for the insulating paper as well as for the correct location of the armatures in an insulating or wedge inserting machine.
The insulating or wedge inserting machines for armatures have the function of inserting in the longitudinal slots of the armatures of electric motors portions of insulating cut paper by a continuous web.
The common main movements of insulating machines are:
feeding the continuous paper beyond a cutting zone,
cutting the paper, normally by means of a cutter,
bending the cut portion,
inserting the cut and bent portion in the slot of the armature, and
indexing or angular positioning the armature.
In wedge inserting machines there is the only difference that the step of bending is missing, since the paper is inserted in the slots of the armature in plane longitudinally embossed conditions.
In known machines of this type all said movements are carried out by a single mechanism with a single drive, comprising cams and gears. This way, it is possible a synchronisation of all the movements and the achievement of high production rates.
Armature production lines, however, are required to work with even much more flexibility and require, furthermore, higher quality of the final product.
The drawback of known machines, however, is that they have not high flexibility in case of change of the dimensions of the armature, since they require always, even if short, a stop time of the production to adjust the strokes of the many parts that carry out the above described movements, according to the dimensions of the armature, among which the stack height, the diameter, the length, etc.
In EP289759 an insulating machine is described for armatures of electric motors having means for measuring the height of the stack of sheets of the armature and a system to stop the insulating paper in order to adjust the length of the cut paper. However, this machine, even if it has a flexibility higher than the previous traditional machines, it does not provide a control of speed, whereby single operations can be repeated only at the same speed of the paper in order to achieve the synchronisation. A variation of speed requires a new adjustment of the machine.
Furthermore the system of inserting paper at variable length of EP289759 is subject to errors owing to variations of coefficient of friction of the paper, since the adjustment of the length is obtained by means of a sliding of the feeding roller on the paper same. As a consequence of this fact the paper shrivels, preventing from, in particular, using different types of insulating paper according to the types of armatures, without setting again the machine.
It is therefore object of the present invention to provide a machine for inserting insulating paper in the slots of armatures of electric motors wherein a high flexibility is possible of choice of the inserting parameters.
It is another object of the present invention to provide a method for operating the devices for feeding, cutting, inserting the insulating paper and for indexing the armatures in an insulating or wedge inserting machine, wherein the automatic change and adaptation of the strokes of such devices according to the dimensions of the armature and the production rate is met.
These and other objects are achieved by the armature insulating machine, of the type that has a plurality of longitudinal slots to line of insulating paper, comprising:
means for feeding a web of insulating continuous paper in a feeding direction;
means for transversally cutting the web into portions of predetermined length;
means for inserting the cut and bent portions into the slots, and
means for indexing the armatures.
Its characteristic is that it further comprises:
means for feeding the web beyond the means for cutting,
means for operating in turn the means for cutting, inserting and indexing,
sensors means suitable for giving a signal proportional to the achievement by the paper of a predetermined position beyond the means for cutting;
electronically programmable means for controlling the means for feeding and the means for operating responsive to said signal so that in turn portions of paper of predetermined length are cut.
Said means for inserting in the insulating machines, differently from the wedge inserting machines, also provides preliminary bending means of the paper according to the shape of the slot in which it has to be inserted.
The electronically programmable means can provide means for synchronising the means for feeding with the means for operating, comprising first encoding means of the means for feeding, second encoding means of the means for operating, a control unit suitable for driving the means for feeding and the means for operating according to a predetermined function responsive to signals coming from the first and second encoding means.
Preferably the means for feeding the web provide a first motor and the means for operating in synchronism the means for cutting, inserting and indexing, provide a second motor along with distribution means for timing in turn the respective movements.
Advantageously, means are provided for carrying out a measurement of the dimensions of the armatures, such as in particular the stack height, the electronically programmable means controlling the means for feeding responsive to this measurement so that portions of paper are cut in turn of corresponding length.
The second means for operating in synchronism the means for cutting, inserting and indexing, can comprise:
means for operating in turn the means for cutting and inserting;
means for operating the means for indexing,
angle sensor means suitable for giving a third signal proportional to the achievement by the armature of a predetermined angular position with respect to the means for inserting;
electronically programmable means for controlling the means for indexing according to the third signal so that a predetermined angular movement of index is given.
In this case, the first means for feeding the web can provide a first motor, whereas the second means for operating in synchronism the means for cutting, bending, inserting can provide a second motor and distribution means for timing in turn the respective movements and the third means for operating the means for indexing can provide a third motor.
The second electronically programmable means can comprise means for synchronising the means for indexing with the means for operating, the control unit driving the means for indexing and the means for operating according to a predetermined function responsive to signals coming from the second encoding means and from the signal of angular position.
Concerning another aspect of the invention, a method for operating the devices for feeding, cutting and inserting the insulating paper as well as for the correct angular positioning of the armatures in an insulating or wedge inserting machine for armatures having a plurality of longitudinal slots comprises the steps of:
feeding a web of insulating continuous paper in a feeding direction;
Transversally cutting the web into portions of predetermined length;
Bending the cut portions according to a bend similar to the cross section of the slots,
inserting the cut and bent portions into the slots, and
indexing the armatures for offering in turn the slots of the armatures among an inserting and the following.
The characteristic of the method is that the following steps are provided:
feeding the web beyond the means for cutting and detection of a first signal proportional to the achievement by the paper of a predetermined position before the cutting;
operating separately and in turn the means for cutting, inserting and indexing, and detection of a second signal on the progress of the operating step,
controlling the feeding and the operating step according to the first and second signal so that portions of paper of predetermined length are cut and inserted in turn.
In this case, the cutting, inserting and indexing steps comprise:
operating in turn the cutting and inserting steps;
operating independently the indexing step,
detecting a signal of angular position of the armature during the step of indexing,
controlling the indexing step responsive to said signal of angular position and stopping of indexing when a predetermined angular position is reached.